Application of a Multiphase Compositional Model for Design of DNAPL Remediation Strategies

E. A. Sudicky, P. A. Forsyth, and A. J. A. UNGER

Many industries produce and store hazardous chemicals, which, when released into the subsurface, form a dense non-aqueous phase (DNAPL) which sinks below the water table. Since DNAPLs are slightly soluble in water, it may take hundreds of years to dissolved the non-aqueous phase source of contamination. During this time, an enormous plume of contaminated groundwater may develop. Consequently, it is highly desirable to remove the DNAPL source as quickly as possible. This paper focuses on simulating remediation strategies for removing the non-aqueous phase contaminant. It must be recognized that in any real situation, there exists substantial uncertainty in many of the model parameters. For example, detailed permeability data are not usually available, and experimental data for three phase relative permeability and capillary pressure are also typically lacking. In this situation, the goal of simulation is to determine a robust remediation strategy. A robust remediation process will be effective in removing the DNAPL contaminant for a wide range of hydrogeologic parameters, and thus will be a good candidate for a remediation strategy for a real site, where such parameters are highly uncertain. A three-dimensional multiphase model is used to simulate a variety of strategies involving vacuum extraction, air sparging, pump and treat, and combinations of these processes. The effect of placement of injector/producers, use of horizontal injectors, and pressures at the vacuum extractor are studied.

AAPG Search and Discover Article #91019©1996 AAPG Convention and Exhibition 19-22 May 1996, San Diego, California